Gaster the Wing Ding Master & U
by atllas
Summary: You were just trying to get home when you came across your first monster. He looked so sad that you just couldn't turn him away. Turns out you're going to get more than you bargained for. Gaster x Reader. Post-Pacifist Ending. Reader is gender neutral with a stutter.
1. Chapter 1

Hi guys, so it's been a while (long long while) since I've ever done any sort of substantial fanfic writing, and Undertale has me smitten so much that I want to break out my typing fingers and try banging out a fic or two.

This is a Gaster x Reader, cause I love me some bone daddy. Reader is address as Y/N, is gender neutral, and has a stutter. There will most likely not be any smut in this, but kissing and fluff most likely. This will be multi chapter, but don't ask about update times, cause even I'm not sure when I'll be updating.

Please let me know what you all think!

* * *

You tuck your face into your scarf as a biting wind blows through the park you were walking through. Winters at Ebott City were always particularly harsh compared to other parts of the country. There used to be fairy tales when you were a kid about how the harsh weather was due to a curse placed on the humans for crimes against monsters thousands of years ago. That's all monsters were back then. Fairy tale creatures, apparitions, boogiemen that go bump in the night to scare kids to go to bed on time. No one expected there to be _actual_ monsters. One day, they just showed up.

Apparently some kid who fell down Mount Ebott broke the barrier that was keeping them all trapped. Part of you was extremely interested in the new life that populated the Earth, you also wondered how an entire civilization could be hiding underneath the city for millennia and not be found. You spent a whole day researching all you could about the monsters, but you gave up when you found out everyone was as clueless as everyone else.

It's been about three months since monsters moved in. Sure, there were a couple riots, and a few hate groups popped up, but nothing more than what usually happens when humanity gets spooked. Quite literally actually, you've seen a few ghost and skeleton monsters around the city. Cool stuff.

You idly checked the timer on your phone, 28 minutes; you made good time at the store today. You still haven't quite beaten your record, but you were close, especially since you had the extra chatty cashier today.

You sort of prided yourself on just how well you can avoid society, you were practically the living embodiment of a shut-in. You had to be- crippling anxiety, depression, and a whopping dose of awkward you so graciously inherited from your father's side of the family completed the mental mess that was…you.

You had been timing how quickly you could shop and get back home. You never really had to go anywhere else besides the grocery store anymore. Clothes and anything else could be bought online, and you were lucky enough to get a work from home job that paid enough for a small apartment in the city. It wasn't much, but it was home.

And oh, you could not wait to be home. You had a box of mac n cheese with your name on it. It was Friday, and you didn't have to log into work for the whole weekend. You almost didn't know what to do with yourself.

You checked the time again and cringed when you saw you were falling behind. You popped in your earbuds and played some fast paced music- that always made you walk faster. Your head bobbed along with the beat as you briskly made your way through the park. It was late, past dark, which meant it was empty. You weren't worried or anything, the neighborhood was a nice one, and you kept a small pocket knife in your bag for emergencies anyway.

What you weren't prepared for however, was the deafeningly loud static that suddenly flooded your earbuds. You yelped and yanked the cords out of your ears on reflex. Grabbing your phone, you paused the music, only to still hear the awful noise still coming through them.

You cursed, these were brand new buds dammit, and they already broke. You pulled the jack out of the phone, and froze. The static still didn't stop. You stared at the cord in your hand, breathing heavily.

This was like something from a horror movie, and you weren't having any of it. You shoved your earbuds and phone back into your pocket and quickly took off, not quite running, but you wanted to when you realized that the static in your pocket was steadily getting louder.

You looked this way and that and you felt tears well up in your eyes at the stress. You were always a bit of a crybaby. Turning toward the exit of the park, you falter and nearly fall to your knees as a terrible screeching filled your head. You dug your palms into your temples, hoping, praying for some sort of relief. Why was it so loud? Why wasn't anyone else freaking out? Surely there would be cars screeching on the road, or people yelling from the god awful noise.

You gasped when all the noise cut out at once. The screeching stopped, your earbuds were silent, and the only thing you could hear was the left over ringing in your own head. You sat where you fell (when did you fall?) and tried to catch your breath.

You kept your palms to your head, dizzy from it all.

You froze again at the sound. It almost sounded like a language, but you couldn't understand it.

You turn from your spot on the ground to the source of the sounds. Behind you was a puddle. An impossibly dark, black puddle. That was bubbling. Why was it bubbling?

You gasped as something started _coming out_ of the puddle. You scrambled back until you hit the lamp post behind you.

"S-Stop! St-Stay a-aw-wway!" Ah yes, that lovely stutter of yours, how intimidating. You blindly went through your bags, looking for your knife. You couldn't tear your eyes away from the slowly forming figure if you wanted to.

You nearly scream again as a white face appears from the ink black, white hands with holes in the middle followed. Black eyes with white pinpricks stared at you. It looked like the ghost from Spirited Away. Or one of those creepy pasta monsters you read about late at night.

You pressed yourself against the lamp post as the creature crept closer and closer to you. It only stopped a foot from your face, and you felt yourself going insane just by staring at the thing. Your vision blurred as tears filled your eyes. This was it, this was how you were going to die. You were staring at some demon spawn like a deer in headlights and it was going to kill you and drag you to hell.

You flinched when one of the hands wiped a tear off your cheek. It was murmuring to itself in that alien language before the pinpricks met yours again. Its mouth stretched from one side of its face to the other in a Cheshire grin that looked way too much like that Jeff the Killer creepy pasta for your liking.

"P-please…" you sobbed as you tried to meld and become one with the pole at your back. Your breaths were shaking and you slowly started to feel yourself fall into a panic attack. The creature had the decency to look similarly panicked at your state. Its hands starting flying around, and it looked like…sign language?

It noticed your attention and stared frantically signing again.

"Um…I-I…I d-ddon't know s-sssign la-aanguage…" You swallowed the growing lump in your throat. Your stutter was coming out full force now.

It looked even more panicked now, turning this way and that, searching for something. It suddenly stopped and turned back to you and you felt _something_ in your pocket moving. You hold down a scream again, only letting out a high pitched whine as your phone floated out of your coat pocket and over to the creature.

It turned your phone around several times before floating it back to face you. The screen glowed bright white and you saw the text that took up the screen.

 **I DID NOT MEAN TO FRIGHTEN YOU.**

 **NO ONE HAS SEEN ME BEFORE.**

…What? You looked from the phone to the creature. Its hands were wringing together and looked nervous, but it seemed to have a hopeful gleam in its eyes. Well, you were still alive anyway, brownie points for the hell demon.

"U-um…" You guessed it couldn't hurt to try to talk to the thing…right? You took a breath to try to calm yourself before continuing. At least you could know what the thing that was going to kill you was.

"A-are…are y-you a uh...a m-m-mmmonster? F-ffffrom the Undergr-ground?"

The thing perked up again and you saw static over your phone before new text appeared.

 **YES.**

 **I AM SORRY FOR SCARING YOU.**

Well, now you just feel like an ass.

Your phone floated closer to you and you reached for it with a shaky hand. You swallowed again and looked at the monster. You let yourself relax slightly. It hasn't killed you yet, and if it _was_ a monster from the Underground, they were peaceful from all the news stories you've read.

"I-it's ok-k-kay. M-mmy nname is Y/N." Your heartbeat slowed to a somewhat normal rate and you found yourself able to breathe a bit easier. You saw your phone static over again and glanced at it.

 **THAT IS A NICE NAME.**

 **MY NAME IS GASTER.**

"O-Oh, it's n-nnice to meet you." You replied quietly and started to stand up. Your legs were still a little wobbly, but you held onto the lamp post for support. The monster, Gaster, looked to you with what looked like concern. You phone staticed over.

 **ARE YOU ALRIGHT?**

You nodded and went to retrieve your bags that fell. As you went to pick one up, you jumped when the items that fell out floated up and collected themselves back into the bag. You looked to Gaster and he had a shy smile, and you gave a small smile back. Huh, definitely not as creepy now compared to earlier.

"Thanks." You straightened out your jacket and situated your bags before turning to the monster. "H-have a good night, sir."

You were about to turn away to walk home when you caught sight of the sad look his face took on. His hands were wringing together again, and he looked gloopier.

Your cousin was right, you were too nice for your own good. You internally sighed and braced yourself.

"Do…you have a-anywhere to go to? Are you s-ssstaying somewhere?"

You felt your phone vibrate in your pocket. Taking it out, you frowned slightly.

 **NO.**

You bit your lower lip in thought. Should you? Could you? You knew you would never forgive yourself if you left knowing he had nowhere to go.

"Um…You can cr-crash at my plllace if you need t-to. If you w-wwant." You felt better when you saw him smile again and looked at your phone when you saw it light up.

 **I WOULD APPRECIATE THAT GREATLY Y/N, THANK YOU.**


	2. Chapter 2

This chapter will be more of a set up for the setting of the readers home. More story progression will occur in the next chapter or two.

* * *

The walk back to your apartment was quiet. Your own inability to hold a conversation paired with the fact that it would probably just look like you would be talking to yourself put a damper on the atmosphere. At least no one bothered you on the way home.

You honestly didn't know why you offered. The apartment was small, he would most likely be staying on the couch (did he even need sleep?) and there was definitely no way, no how you were giving up your own bed. There had to be a line drawn somewhere. He would have a roof over his head, food in his…well you'll find out if he even eats soon anyway, and he won't be out in the cold. The deed would be good for your karma.

You repositioned your bags to your other hand. Gaster had been kind enough to ask if he could carry anything, but you declined. Having floating bags of groceries would look strange, and you're already scared of people looking at you as is.

"Here we are…" you murmured quietly as you made your way into the building. It was old, but held up rather well. No mold or any issues like that, and the landlord and his wife were nice people. Your neighbors were decent, but you never really talked to them anyway, and they were quiet which was always a plus.

You sighed as you prepared yourself for the hike up the stairs to the fifth floor. There was an elevator, but you figured this was the only amount of exercise you get, so you might as well suffer a bit as payment for the laziness. Gaster was silent for the whole trek, the only reason you knew he was still following was the static you could feel in the air. You internally twitch- it was starting to make your hair frizz.

And there they were. Room 504. You felt like you needed a drum roll. Then you felt your stomach drop to your feet. When was the last time you tidied up?

You could already feel a flush of embarrassment begin as you unlocked the door and stepped in. Taking a quick glance around, you found that it wasn't _too_ bad. Some clothes strewn about, the coffee and kitchen tables were littered with papers and old mail, but it was nothing you couldn't shove in a closet somewhere out of the way.

"Mmmake yourself at h-hhome." You walked through the living area to the open kitchen on the other side of the space, hefting your groceries onto the counter to be put away. Looking over, you saw Gaster glide (or was he floating?) into your apartment, turning this way and that. He seemed curious, but didn't say anything. "S-sorry for the m-mess. Wasn't expecting company…" you trailed off into a murmur as you hung your jacket up and started putting the food away. Gaster nodded and went to sit on the couch, still silent.

Oh, wait. You couldn't understand him without your phone. You quickly pull the thing out and made a show of putting it on the counter for him to see. He could say something if he wanted to, but the silence didn't bother you in the slightest. You were just finishing putting away the pantry items when you heard the phone vibrate against the wood.

 **THANK YOU AGAIN FOR ALLOWING ME TO STAY.**

You give him a small smile and turn to the living area where Gaster was seated. He wasn't as goopy as he was when at the park, though he still had the strange grin on his face. Of all the monsters you've seen walking around the city, none have ever looked like him. You're snapped out of your thoughts when Gaster clears his throat- at least that's what you thought that staticy noise was, and you realized you were staring. Wow, rude. You mumble a quick apology and gesture down the hall.

"Fffirst door on the right is the bathroom if you ne-need it. The oo-one on the right is my office and the one down from that is mmmy room. I uh, d-don't have a spare bbbedroom or anything, I hope yyyou don't mind the c-couch. I'll get you some e-extra blankets and ppp-pillows." You take a deep breath from your diaphragm, trying to ease yourself from the stutters. Talking for long sentences always left you breathless.

You glace at your phone when you feel it vibrate in your pocket. Gaster smiled at you again from his spot in the living room.

 **THE COUCH IS MORE THAN ENOUGH, THANK YOU.**

"Do uh…you ww-want anything to e-eat? I was g-going to mmmake mmac and ch-cheese." You catch yourself fiddling with the sleeve of your top and go to move back to the kitchen taking your phone with you.

 **I WILL HAVE WHATEVER YOU MAKE.**

Well, he was a polite thing wasn't he? You grab the supplies for dinner and hear shuffling from Gaster. You glance at your phone from its spot on the counter.

 **WOULD IT BE OKAY IF I LOOKED AROUND A BIT?**

You give the a-okay and turn back to the food. Since you had company you figured you would spice dinner up a bit. How you could spice up a box of mac n cheese dinner, who knew, but you would make an effort anyway. You tossed in some fancier shredded cheese, popped some more on top along with some bread crumbs, and popped all that into the oven on broil for a few minutes. Tada, fancy macaroni and cheese. You puffed your chest out a bit with pride at your culinary skills. Cooking was one of your few talents you would ever willing brag about.

You heard Gaster enter the office as you were cooking. You set the timer for the oven and move to see what he was up to, but not before doubling back for your phone you forgot.

He was hunched over in front of your computer, just looking at it. You knocked on the door frame to get his attention. He jumped and whipped around to look at you, seeming embarrassed. You feel your phone vibrate and glance at it.

 **FORGIVE ME, I WAS ADMIRING YOUR ELECTRONICS.**

Oh, your electronics. Your computer was essentially your child, and you coddled it daily. You built the thing yourself and didn't skimp when it came to price for the parts. From your mouse and keyboard to your headphones and webcam, you made sure they were top quality. It was also probably the cleanest are of your apartment, you kept your desk spotless, lest any contaminates mess with your baby.

You get a split second panic at the thought what he was going to ask to use it. As nice as he was, and as nice as you liked to think you were, you couldn't bring yourself to let someone else use your child. Fear of viruses or malware made your eye twitch.

You move around Gaster and reach into one of the boxes you keep next to your desk. Pulling out your old laptop and charger, along with the wireless mouse, you gesture to the monster next to you.

"You c-can use this if you wwant. I don't really use this ttthing anym-more." And you didn't. The laptop was old and way too outdated to be of any significant use, you just kept the thing around for emergencies or if you had to travel. Which wasn't often.

Gaster smiled and accepted the electronics and you both headed back into the living room. You stopped to grab a pillow and blanket out of the hall closet. He inclined his head as thanks and settled back onto the couch, laptop on the coffee table in front of him. The timer went off and you went off to tend to dinner. You fixed up two bowls and two glasses of water before heading to the couch. Gaster was hunched over the laptop, focusing on reading some strange text you couldn't read. Quiet mumbling came from him and you simply set his dinner next to him before sitting in the recliner next to the couch to eat your own food.

You settled in and started some space documentary on Netflix while Gaster toiled away on the laptop. It wasn't until you were nearly complete with your dinner that he seemed to snap out of the daze he fell into and began eating his own. You tried not to stare, you really did, but it was somewhat fascinating, if not a little terrifying, seeing the way he ate. His mouth opened to more black void. No teeth, no tongue or gums, just black. You suppress a shiver and stood to take your dishes to the kitchen before returning to finish watching tv. Gaster seemed interested in the documentary so you set a queue to play a few more afterwards as well.

The rest of the night was spent in relative silence. You asked if he needed anything, but he declined nearly everything. Eventually you bid him goodnight and went to your room to pass out. Gaster smiled and inclined his head as a farewell before turning back towards the laptop. Maybe he could just have the thing. You wouldn't mind. You made sure to close your door to your room though, at least you could hope to hear the door if he or anyone else tried to come in. Couldn't be too careful, regardless of how nice he seemed.

You settled in and wondered what to do tomorrow. You had the day free, but with your new guest, you weren't so sure what the day would entail. Couldn't be that bad.

Could it?


End file.
